A socket may be provided to electrically connect an object to be connected to a circuit board. The socket may have a connecting terminal to be in contact with the object to be connected. In this case, the connecting terminal is preferably less apt to be affected by noise.
For example, Japanese Laid-open Patent Publication No. 2008-96390 discloses a test socket using a pogo-pin type contact probe (a movable contact probe whose tip end can elongate and contract) as the connecting terminal. According to a technique disclosed in Japanese Laid-open Patent Publication No. 2008-96390, an inductance can be canceled out by providing a capacitor between the adjacent pogo-pin type contact probes. With the technique, the impedance of the contact probe in which the capacitor is provided may be decreased to thereby reduce the noise in the contact probes.
For example, Japanese Patent No. 2856706 discloses a CPU socket (a PGA socket) in which through holes as many as the pins of a LSI for a CPU are provided in a multilayer board, contacts (connecting terminals) are inserted into the through holes, contact lead wires connected to the contacts are pulled out of a lower surface of the multilayer board, and the contacts are electrically connected to a stacked capacitor formed of electrode layers and dielectric layers. According to a technique disclosed in Japanese Patent No. 2856706, impedance of the contacts electrically connected to the stacked capacitor is decreased to thereby reduce noise of the contacts.